Lots of spent on mods and "improvements".
If you don't baseline and then quantify the impacts, you never know if the bang is worth the buck.
That's big value of the forum - not everyone has to experiment - we can learn from others that do it right and have the data from measured results to back it up.

Lots of spent on mods and "improvements".
If you don't baseline and then quantify the impacts, you never know if the bang is worth the buck.
That's big value of the forum - not everyone has to experiment - we can learn from others that do it right and have the data from measured results to back it up.

It's worth pointing out, however that FCA does make and include a finned aluminum diff cover on certain 3500 DRW trucks. I don't think there is a capacity difference though. Obviously Ram engineers think there is some benefit to cooling, the question is does the added capacity found in aftermarket covers do anything beneficial? I have no need for differential sight glasses, dipsticks, or drain holes.

The ring gear is throwing viscous oil that takes time to drain back to the bottom of the diff housing. Faster ring gear, throws more oil. I’d never really considered that, but it isn’t so crazy when you think about it.

Lots of spent on mods and "improvements".
If you don't baseline and then quantify the impacts, you never know if the bang is worth the buck.
That's big value of the forum - not everyone has to experiment - we can learn from others that do it right and have the data from measured results to back it up.

It's worth pointing out, however that FCA does make and include a finned aluminum diff cover on certain 3500 DRW trucks. I don't think there is a capacity difference though. Obviously Ram engineers think there is some benefit to cooling, the question is does the added capacity found in aftermarket covers do anything beneficial? I have no need for differential sight glasses, dipsticks, or drain holes.

I only see larger capacity being beneficial for really short duration events that generate a lot of heat. A larger volume of oil gives you a larger heat sink to accept short intervals of high heat rate that might cook a smaller volume of oil if the rate of heat rejection from the housing can’t keep up. For long term, steady state conditions, that bigger heat sink means nothing. It becomes a matter of heat transfer to the outside by (mostly) convection, driven by material, surface area, and air flow (including where/how that air is impinging the surfaces). As Banks suggested (I did watch it, couldn’t help myself), the ass end of a differential really isn’t getting the best cooling air flow. It really wouldn’t surprise me if more heat is getting pulled out of the front of the differential housing than the rear at highway speed. Larger surface area, directly impinged by the air flow.

The ring gear is throwing viscous oil that takes time to drain back to the bottom of the diff housing. Faster ring gear, throws more oil. I’d never really considered that, but it isn’t so crazy when you think about it.

Lots of spent on mods and "improvements".
If you don't baseline and then quantify the impacts, you never know if the bang is worth the buck.
That's big value of the forum - not everyone has to experiment - we can learn from others that do it right and have the data from measured results to back it up.

It's worth pointing out, however that FCA does make and include a finned aluminum diff cover on certain 3500 DRW trucks. I don't think there is a capacity difference though. Obviously Ram engineers think there is some benefit to cooling, the question is does the added capacity found in aftermarket covers do anything beneficial? I have no need for differential sight glasses, dipsticks, or drain holes.

I only see larger capacity being beneficial for really short duration events that generate a lot of heat. A larger volume of oil gives you a larger heat sink to accept short intervals of high heat rate that might cook a smaller volume of oil if the rate of heat rejection from the housing can’t keep up. For long term, steady state conditions, that bigger heat sink means nothing. It becomes a matter of heat transfer to the outside by (mostly) convection, driven by material, surface area, and air flow (including where/how that air is impinging the surfaces). As Banks suggested (I did watch it, couldn’t help myself), the ass end of a differential really isn’t getting the best cooling air flow. It really wouldn’t surprise me if more heat is getting pulled out of the front of the differential housing than the rear at highway speed. Larger surface area, directly impinged by the air flow.

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I installed a diff cooler on my Nismo. That diff is up out of the air flow. Plus it has 2, 3" exhaust pipes right next to it. It used to have a VLSD. When it got hot. It turned into a one wheel peeler. The VLSD just quit working the way it should. So I installed a OS Giken LSD. That LSD uses 75w-250 gear lube. With the diff cooler. On the track. It will get up to 270F. I can turn the diff cooler on, and it will drop the temps down to 145F after about 10 minutes. The most I've seen on the street is 255F after running 4 hrs at 80 mph.

As an ex-test engineer for Dana corporation in Toledo, I am calling BS on this (and yet another reason I think Gale Banks is a better salesman than engineer...).

I've personally seen the difference on an M44 rear end, one with a cast aluminum finned cover, and the same axle with a stamped steel cover, towing the same load, under the same conditions, on the same track... The finned cover consistently saw 20-30*F cooler temps than the stamped steel cover at highway speeds (70mph), towing 7500lbs, with an 8'x8' wind sail. This was on a Titan test truck (not truly a standard M44, but that's irrelevant).

Now, did the axle live longer because of those lower temps? I have no idea... the truck caught on fire and burned to the ground before we finished the testing... but, the finned cover definitely lowered the temps of the gear oil.

Now, we never tested aftermarket pans, and I can tell you there is a scientific method to the design of the fins, so perhaps aFe's don't work as well as a factory designed pan.

Also, increased capacity has no effect on the steady state temperature of the oil (negating the minimal increase in effective transfer area of the oil to the case). Power through the R&P, along with the bearing losses, remains constant (increased capacity may actually increase these losses due to drag). Those losses create thermal energy, which can be measured (like in watts). The time it takes to heat the oil to steady state may change, but the thermal transfer coefficient doesn't with a capacity change alone (again, negating minor variances in material transfer areas). So, adding volume won't lower temperatures, by itself.

Changing the thermal transfer coefficient, and emissivity of the cover/housing, absolutely, without question (and according to the laws of physics), will effect the steady state oil temperature. Aluminum has a MUCH higher thermal transfer coefficient than steel. And while the machined fins look cool, black paint would improve it's radiant emissivity more-so than raw aluminum (though some paints are also good thermal insulators, so paint choice can have large effect).

As an ex-test engineer for Dana corporation in Toledo, I am calling BS on this (and yet another reason I think Gale Banks is a better salesman than engineer...).

I've personally seen the difference on an M44 rear end, one with a cast aluminum finned cover, and the same axle with a stamped steel cover, towing the same load, under the same conditions, on the same track... The finned cover consistently saw 20-30*F cooler temps than the stamped steel cover at highway speeds (70mph), towing 7500lbs, with an 8'x8' wind sail. This was on a Titan test truck (not truly a standard M44, but that's irrelevant).

Now, did the axle live longer because of those lower temps? I have no idea... the truck caught on fire and burned to the ground before we finished the testing... but, the finned cover definitely lowered the temps of the gear oil.

Now, we never tested aftermarket pans, and I can tell you there is a scientific method to the design of the fins, so perhaps aFe's don't work as well as a factory designed pan.

Also, increased capacity has no effect on the steady state temperature of the oil (negating the minimal increase in effective transfer area of the oil to the case). Power through the R&P, along with the bearing losses, remains constant (increased capacity may actually increase these losses due to drag). Those losses create thermal energy, which can be measured (like in watts). The time it takes to heat the oil to steady state may change, but the thermal transfer coefficient doesn't with a capacity change alone (again, negating minor variances in material transfer areas). So, adding volume won't lower temperatures, by itself.

Changing the thermal transfer coefficient, and emissivity of the cover/housing, absolutely, without question (and according to the laws of physics), will effect the steady state oil temperature. Aluminum has a MUCH higher thermal transfer coefficient than steel. And while the machined fins look cool, black paint would improve it's radiant emissivity more-so than raw aluminum (though some paints are also good thermal insulators, so paint choice can have large effect).

Have I mentioned as an ex-Cummins fanatic, I don't like Gale Banks?

Isn't that what I said above? Aluminum conducts heat better than steel, Ram installs aluminum diff covers on 3500 duallies.

Dipsticks, sight windows, extra drain plugs, and fuzzy dice are all worthless on a differential with a removable cover. That pretty well makes AFE diff covers a waste of money.

As an ex-test engineer for Dana corporation in Toledo, I am calling BS on this (and yet another reason I think Gale Banks is a better salesman than engineer...).

I've personally seen the difference on an M44 rear end, one with a cast aluminum finned cover, and the same axle with a stamped steel cover, towing the same load, under the same conditions, on the same track... The finned cover consistently saw 20-30*F cooler temps than the stamped steel cover at highway speeds (70mph), towing 7500lbs, with an 8'x8' wind sail. This was on a Titan test truck (not truly a standard M44, but that's irrelevant).

Now, did the axle live longer because of those lower temps? I have no idea... the truck caught on fire and burned to the ground before we finished the testing... but, the finned cover definitely lowered the temps of the gear oil.

Now, we never tested aftermarket pans, and I can tell you there is a scientific method to the design of the fins, so perhaps aFe's don't work as well as a factory designed pan.

Also, increased capacity has no effect on the steady state temperature of the oil (negating the minimal increase in effective transfer area of the oil to the case). Power through the R&P, along with the bearing losses, remains constant (increased capacity may actually increase these losses due to drag). Those losses create thermal energy, which can be measured (like in watts). The time it takes to heat the oil to steady state may change, but the thermal transfer coefficient doesn't with a capacity change alone (again, negating minor variances in material transfer areas). So, adding volume won't lower temperatures, by itself.

Changing the thermal transfer coefficient, and emissivity of the cover/housing, absolutely, without question (and according to the laws of physics), will effect the steady state oil temperature. Aluminum has a MUCH higher thermal transfer coefficient than steel. And while the machined fins look cool, black paint would improve it's radiant emissivity more-so than raw aluminum (though some paints are also good thermal insulators, so paint choice can have large effect).

Have I mentioned as an ex-Cummins fanatic, I don't like Gale Banks?

What's your beef with Banks? Never bought or used his products. Was thinking on getting a few things for my 6.7 motorhome.

IMHO, most people, including me, install these with the hopes of prolonging the life of the rear axle & its internals. I have 3 different temp gauges, so i KNOW that my numbers are not that far off exact. The rear axle in my particular truck may not have been set up to run optimally, as the temp readings are consistently higher than most. I have seen temps of 315*F while towing our old toy hauler, with a 1150 lb minimum tongue weight. Our new downsized camper only has a "350 lb tongue weight", yet will squat my truck to below level, without the WDHitch engaged. If i stay at 65 mph when towing it, it will read 175*F-187*F on a 70+* summer day. If i speed up past 65 mph AT ALL, the temps rise very fast, meaning just 70 mph will bring readings of 215*F minimum up to 250*F. It has been verified with temp readers of the digital laser type, digital probe type & analog probe type and also blisters on my hand when i touched it by mistake & even sizzled when i wet my finger & touched it when it was 315*F. So yeah, diffs get plenty hot. It seems to me that the lower the gearing you have (higher numerically: i.e. 4.56-5.38) the more speed has an impact on temps. I also had a neighbor that had an old Suburban with 4.56's & towed with it. His experience was the same, anything over 65 mph seemed to drastically increase rear diff temp.

At the very least, I am hoping that the increased oil volume will: 1) provide enough oil to proper lubricate the pinion gear while doing 65 mph towing. 2) provide increased oil life just because you double the volume. I have been changing the rear diff fluid almost every year in my truck. Cheap insurance IMHO. Google "Dodge rear axle failures" & you will get 1,130,000 hits in .46 seconds. I have researched this extensively before i bought my first dodge truck in 2000. Every single failure that meets these critera, had the EXACT SAME RESULT : bought brand new, 1 owner, nobody but dealer ever touched the truck for service, diff filled to factory specs, no leaks in rear axle, still under warranty. The "official results" --- "pinion failure due to lack of lubrication". So, if the truck was bought new, filled to spec, never touched by anyone but dealer, no leaks, how could this possibly happen ??? I am all ears ????

Temp with my new diff cover is the same when highway driving with camper. I have tried LOTS of different types of full synthetic oil. Mobil 1, Valvoline, Mopar, Royal Purple, Amsoil & a few generic full synthetics as well. Some run cooler than others but not by a whole lot, maybe 25*F or so. What HAS made a difference in oil life for me is adding 1 qt of Lucas Lube 140w gear oil to what ever oil i put in my rear diff. It let me go from 12k diff oil changes to 24k oil changes. You can tell when your rear diff oil has sheered by the clicking sound when you turn left or right on pavement. I change the oil & sound is gone for another 24k. Had the same issues on all 3 of my dodge trucks. Towed with all 3, never had any axle failures, at all. Never replaced an axle seal either, even though i purposely overfilled them (also made sure the axle vent was not blocked by mud, road debris or insects)...until i put the Mag-Hytec cover on, which doubled the fluid capacity from 3 to 6 qts.

Your results may vary.

Traded to 2019 ZR2, Red.

4Runner was a GREAT vehicle but could not even tow our 6x10 enclosed utility trailer comfortably, even when it was empty-ish.

It was time. Truck was still leaking BADLY every time it rained or snowed & melted. It was leaking at every single gasket (rear window, front window, all 4 doors). You could sit inside & watch it run down the inside of windshield, rear window & drip off the upper side door beams. It was molding on the inside & starting to stink. Needed new steering gearbox, shocks, new upgraded T-style steering, tires, brake lines, d/s manifold bolts that are barely recognizable due to rust-removed & replaced. Everyone around here would not even touch em once they looked at them.

So, say what you will. PW turned into a money pit. Was no longer a joy to drive. Hoping that this downsized 4x4 with lockers will fill the bill & have minimal problems, but..... As long as manufacturers keep making engineers design things that fail soon after warranty is up, we are going nowhere fast. Regardless of what you buy.

4Runner was a GREAT vehicle but could not even tow our 6x10 enclosed utility trailer comfortably, even when it was empty-ish.

It was time. Truck was still leaking BADLY every time it rained or snowed & melted. It was leaking at every single gasket (rear window, front window, all 4 doors). You could sit inside & watch it run down the inside of windshield, rear window & drip off the upper side door beams. It was molding on the inside & starting to stink. Needed new steering gearbox, shocks, new upgraded T-style steering, tires, brake lines, d/s manifold bolts that are barely recognizable due to rust-removed & replaced. Everyone around here would not even touch em once they looked at them.

So, say what you will. PW turned into a money pit. Was no longer a joy to drive. Hoping that this downsized 4x4 with lockers will fill the bill & have minimal problems, but..... As long as manufacturers keep making engineers design things that fail soon after warranty is up, we are going nowhere fast. Regardless of what you buy.

I'm starting to think about my locker issue I had this summer. I have a Rock Crusher diff covers on both front and rear. But they are almost the same shape as the stock covers. The only real difference is that the fill plugs are higher on the Rock Crushers. The issue I was having. On my trip out west. My rear locker light would flash after about a 100 miles of steady state driving at 70 mph, and would stay flashing. The next morning. The same thing. Would have to drive about a hundred miles before it would flash. Haven't done a thing to the diffs since that trip, and my locker light no longer flashes. Haven't driven over 50 miles per trip since then. Everything with them is ok. Everything works as it should. The only thing I did before the trip, was to change the lube in them. Mobil 1 75w90, 3 quarts in the front and 6 quarts in the rear. The same as I first installed the diff covers. Wondering now if my level is too high and causing too much heat. Affecting the locker sensor? Or my rotted tail pipe blowing exhaust on the right side axle tube. Which is fixed now.

The benefits of increased capacity may be debatable, but the benefits of a drain plug to me aren’t, and that’s why I have Mag-Hytecs, at least in theory: they mis-engineered their drain plugs, and I have stripped the woefully inadequate 3/16 hex fittings on both.